Glasses and spectacles are well known in the art and they all suffer from the same drawback: when a user wishes to wear the glasses, he/she needs both hands to unfold the arms from their folded position (which is used when the glasses/spectacles are stored).
This can be difficult when the user does not permanently wear his glasses and is occupied with at least one hand, for example when driving a car or holding a phone, and the user needs his glasses because of the sunlight (while driving) or if he wants to read a text message received on his phone or the name of a caller.